Electric-lighting system



Sept. 25, 1928.

R. H. SULLIVAN ELECTRI QLIGHTING SYSTEM Filed March 1'7, 192'? llmwcennttanm Patented Sept. 1928.

' UNITED s 'rA'ras PATENT OFFICE.

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Application at much 11, 1921, Serial no. 170,205.

This invention relates to electric lighting systems for motor-vehicles, of the type in which a generator, connected with the engine and driven at variable speed, is used without a storage-battery to supply the lights at substantially constant volta e.

In a system of the kin in question it is customary to control the voltage by means of a regulator of the vibratory relay type, which controls the current throu h a shunt winding of the generator, and to re i'eve this regulator -of a part of the load which would otherwise be thrown upon it, the shunt windingmay be ener 'zed through a third or supplementary l5 brus in the generator, so that the regulation is partly inherent.

While a vibratory regulator, in a system of the kind in question, will hold the average voltage suflic'iently constant, its pulsatory to mode of operation necessarily results in momentary recurrent fluctuations of voltage above and below normal, and in the absence of a battery these fluctuations tend to cause flickering in the lamps. The object of the 26 present invention is to eliminate such flickering or to reduce it to an unobjectionable minimum, and this is accomplished by the use of a small resistance load which is so connected with other parts of the system that it accomplishes the desired result with the minimum consumption of energy and without substantially reducin the eifective voltage at low generator spec s.

The accompanying drawing is a diagram of 5 a s stem embodying the invention.

n the system illustrated the variable-speed generator 1 has main brushes 2 and 3, a third or auxiliary brush 4, a shunt winding 5, which is, energized by connection with the third 4" brush, and a cumulative series winding 6. The output of the generator is conducted through main conductors 7 and 8, across which the lamps 9 are connected, the lamps being thrown on and oil by means of a load 45 switch 10.

The vibratory regulator has a magnet winding 11 connected across the main conductors 7 and 8, so as to be responsive to the voltage across these conductors. The arma-' m ture 12 of the regulator cooperates with a fixed contact 13, which is connected with the shunt winding 5 throu h a wire 14, a switch 15 and a wire 16, whi e the armature 12 is connected, through a wire 17, with the load conductor 7 and the'main brush 2. When the switch 15 is closed the shunt winding is thus connected between the third brush 4 and the niain'brush 2. The switch 15 is used in order that the field-winding of the generator may be entirely de-energlzed at the same time when the load is disconnected from the generator, and for this purpose the switches 10 and 15 are shown as mechanically interconnected.

Whenever the generator voltage across the main conductors tends to rise above the predetermined maximum, the regulator opens the shunt field circuit, this action being only momentary, however, since the voltage at once falls and permits the regulator armature again to engage the contact 13. The regulator thus operates in the ordinary manner of a vibratory regulator. To reduce the sparking at the regulator contacts a resistor 18 is preferably connected across these contacts.

The novel feature of the invention resides in the use, in connection with the system described and illustrated, ofa small resistance load in the form of a resistor 19, which is connected directly between the third brush 4 and the main brush 3. This main brush is the trailing brush, as indicated by the arrow which shows the direction of rotation of the armature, and the third brush is so adjusted that the main brush 3 is the one which, at least at the lower speeds of the generator, has a potential more nearly equal to that of the third brush. When the generator is running at a low speed, sufiicient only to furnish the necessary voltage for operating the lamps, the difference in potential between the brushes 3 and 4 is so slight that only a small amount of current passes through the resistor 19, and thus the minimum speed at which the generator can effectively energize the lamps is not substantially changed. At this time, however, the regulator contacts remain constantly closed, owing to the fact that the generator voltage is at or below the predetermined max imum, so that the resistance load is practimu cally ineffective only at the time when its operation is unnecessary. As the generator speed increases, however, and the regulator comes increasingl into operation, the tendency to voltage uctuations, due to the vim5 bratory action of the regulator, becomes increasingly pronounced. At the same time, however, owing to the increasing distortion of the generator field through armature reaction, the difference in potential between the no brushes 3 and 4 increases thus increasin the flow of current through the resistor 19. his resistor therefore functions with an increasing effect as a stabilizing load. The effect of the resistor is thus automatically adjusted so that energy is expended only in proportion as required, and chiefly at a time when the gener ator is operating at a speed which permits it to supply this energy in addition to that required for the operation of lamps.

The invention claimed is 1. In a. system of the kind described, the combination, with a variable-speed generator of the three-brush type, a lamp-load supplied by the generator, and a vibratory voltageregulator controlling the current through a field-winding oi the generator, of a stabilizing resistance load connected directly between the third brush and the trailing main brush of the generator.

2. In a system of the kind described, the combination, with a variable-speed generator of the three-brush type having a shunt winding, fed through the third brush, and a cumulative series winding, and with a vibratory voltage regulator controlling the current through said shunt winding, and a lamp-load connected with the main brushes of the generator in series with said series winding, of a stabilizin resistance load connected directly 30 between t 1e third brush and the trailing main brush of the generator.

RAYMOND H. SULLIVAN. 

